The general aims of this project is to advance our understanding of the extrinsic regulations, humoral and cellular, that apply to neurons and glia cells during development and adult life. The objective will be pursued by the investigation of neuronotrophic agents controlling survival, neuritic outgrowth and transmitter function in cultured neurons. Specificially, work will be continued on the elucidation of the cellular and molecular events that link the encounter of Nerve Growth Factor with its target neurons and the earliest consequences of such encounter known thus far, i.e., changes in permeation properties of the neuronal membrane. In addition, different biological materials recently found to ensure survival of ciliary ganglionic neurons in monolayer will be further investigated to uncover similarities and, dissimilarities of their trophic constituents, and of the morphological and biochemical responses elicited by them from the ciliary cells. Lastly, presumptive glial cells from several chick embryo neural tissues have revealed differential responses to different sera with respect to survival and growth, and such cultures will be used to investigate the responsible serum constituents.